Biomedical subjects

Thomas Mentzel

Publications and source records attributed to Thomas Mentzel.

24 records · Page 2Linked to original sources

PubMed2003

Mutations of the BRAF gene in benign and malignant melanocytic lesions.

A single-point mutation in exon 15 of the BRAF gene has recently been reported in a high percentage in cultured melanoma cells and in 6 of 9 primary melanomas examined. To evaluate the impact of the T1796A BRAF mutation, we screened primary melanomas, various types of nevi and lesions where a melanoma developed in an underlying nevus. We could detect the mutation in 28 of 97 (29%) melanomas and in 39 of 187 (21%) nevi, including blue nevi (0/20) and Spitz nevi (0/69), which did not carry the mutation. In melanomas with an underlying nevus, either the mutation was present in both the laser-microdissected nevus cells and the laser-microdissected melanoma cells (3/14) or both lesions were negative for the BRAF mutation except one case. In conclusion, mutations in exon 15 of the BRAF gene are nonspecific for progression of a nevus to a melanoma. Other so far unknown cofactors seem to be of importance.

Exons↗

PubMed2003

[Nephrogenic fibrosing dermopathy].

Nephrogenic fibrosing dermopathy (NFD) is a scleromyxoedema-like disease favoring the extremities and trunk. Histologically there is a cellular fibrosis throughout the entire dermis. NFD is associated with renal insufficiency and dialysis, although the pathogenesis has not been elucidated. A 71-year-old woman developed classical symptoms of NFD on both legs within a few weeks after initiation of hemodialysis and concomitant antibiotic treatment followed by presumed drug eruption.

Aged↗

PubMed2002

Atypical lipomatous tumor in a 14-year-old patient: distinction from lipoblastoma using FISH analysis.

Liposarcomas are rare in young age. We present the rare case of an atypical lipomatous tumor (synonym: well-differentiated lipoma-like liposarcoma) in a 14-year-old girl with the differential diagnosis of lipoblastoma which was excluded by fluorescence in situ hybridization (FISH) analysis. The tumor presented as a soft tissue mass at the dorsal part of the right thigh measuring up to 18 cm. Microscopically the lesion consisted of atypical adipocytes with hyperchromatic nuclei and additional multivacuolated lipoblasts. Interphase dual-color FISH performed with chromosome 8 centromeric and YAC164H5 (mapping to exons 2-5 of the PLAG1 gene) probes revealed no rearrangement of PLAG1 oncogene or polysomy of chromosome 8. Additional FISH using an MDM2 gene probe and an BAC534N15 probe (containing sequences specific for the CDK4 gene) showed amplification of the CDK4 gene. These findings indicate that this tumor was no lipoblastoma but an atypical lipomatous tumor, which is of clinical relevance. In young individuals the distinction between lipoblastoma and liposarcoma is often impossible by light microscopy alone. This case shows that FISH can serve as a decisive tool in the differential diagnosis of lipoblastoma and lipoma-like liposarcoma apart from its role in distinction between lipoblastoma and myxoid/round cell liposarcoma.

Adolescent↗

PubMed2002

CD34-positive glomus tumor: clinicopathologic and immunohistochemical analysis of six cases with myxoid stromal changes.

BACKGROUND: Glomus tumors are benign, mainly superficially located perivascular neoplasms, composed of cytologically characteristic neoplastic cells staining immunohistochemically positive for vimentin and muscle actin, closely associated with often branching blood vessels. METHODS: Six cases of glomus tumor were analysed histologically and immunohistochemically. RESULTS: We report six cases of glomus tumor (three solid glomus tumors, two glomangiomas, one glomangiomyoma) arising on the fingers of adult patients (five female and one male patient; age range 35-65 years) that showed prominent myxoid stromal changes and immunohistochemically a coexpression of alpha-smooth muscle actin and CD34 by neoplastic cells. CONCLUSIONS: Neoplastic cells in glomus tumor may show a coexpression of alpha-smooth muscle actin and CD34, an important finding regarding the differential diagnosis of these lesions and the relationship of perivascular neoplasms.

Actins↗

PubMed2002

Acquired elastotic hemangioma: A clinicopathologic variant of hemangioma.

BACKGROUND: In recent years, many new cutaneous vascular proliferations have been described. This is partly due to the current epidemic of AIDS, which has forced dermatopathologists to establish the diagnosis of the earliest patch-stage lesions of AIDS-related Kaposi's sarcoma and some of the recently described cutaneous vascular proliferations that may histopathologically mimic lesions of early Kaposi's sarcoma. OBJECTIVE: This article reports the clinical, histopathologic, and immunohistochemical findings in 6 cases of a clinicopathologic variant of cutaneous hemangioma, which we have named acquired elastotic hemangioma. METHODS: Six cases of acquired elastotic hemangioma were studied from clinical, histopathologic, and immunohistochemical standpoints. The histopathologic differential diagnosis with other similar cutaneous vascular proliferations is discussed. RESULTS: Acquired elastotic hemangioma appears on the sun-damaged skin of the dorsal aspect of the forearms or on the lateral aspects of the neck of middle-aged or elderly women. Clinically, lesions present as solitary erythematous plaques with variable morphology and in only some cases have a clearly angiomatous appearance. On histopathologic examination, acquired elastotic hemangioma is characterized by a band-like proliferation of capillary blood vessels involving the superficial dermis and arranged horizontally parallel to the epidermis. CONCLUSION: Acquired elastotic hemangioma is a distinctive clinicopathologic variant of hemangioma that should be differentiated from other cutaneous vascular proliferations. On histopathologic examination, it is characterized by capillary proliferation involving the dermis.

Aged↗

PubMed2002

Benign vascular proliferations in irradiated skin.

Several types of cutaneous vascular proliferations have been described in areas of irradiated skin, including both benign lesions, such as benign lymphangiomatous papules, atypical vascular lesions, or benign lymphangioendothelioma, and malignant neoplasms such as high-grade angiosarcomas. This report describes the clinicopathologic features of 15 cases of different types of benign cutaneous vascular proliferations arisen within irradiated skin. All patients were female ranging in age from 33 to 72 years, and they had received postoperative external radiotherapy for treatment of breast carcinoma (14 cases) or ovarian carcinoma (one case). In those cases in which the latency interval period between radiotherapy and the development of the vascular lesion was known from the clinical records, the latency interval period elapsed between radiotherapy and diagnosis of the vascular lesion ranged from 3 to 20 years. The most common clinical presentation of the cutaneous lesions consisted of papules, small vesicles, or erythematous plaques on the irradiated field. Histopathologically, most lesions consisted of irregular dilated vascular spaces, with a branching and anastomosing pattern, thin walls, and lymphatic appearance involving the superficial dermis. A discontinuous single layer of endothelial cells with flattened nuclei lined these vascular channels, and numerous small stromal papillary formations also lined by endothelial cells projected into the lumina of the dilated lymphatic vessels. These cases were classified as benign lymphangiomatous papules or plaques. Two cases showed different histopathologic findings because they consisted of poorly circumscribed and focally infiltrating irregular jagged vascular spaces involving the entire dermis and lined by inconspicuous endothelial cells. In some areas these irregular slit-like vascular spaces dissected collagen bundles of the dermis. These cases were classified as atypical vascular proliferations mimicking benign lymphangioendothelioma or patch-stage Kaposi's sarcoma. All cases showed similar immunohistochemical findings and the endothelial cells lining the vascular spaces expressed immunoreactivity for CD31, but they stained only focally positive for CD34 or were negative for this marker. Immunohistochemical investigations for alpha-smooth muscle actin failed to demonstrate a complete peripheral ring of actin-positive pericytes in most of the neoformed vascular structures. This immunohistochemical profile also supported the lymphatic nature of these vascular proliferations developed in irradiated skin. Although some of these lesions may mimic histopathologically patch-stage Kaposi's sarcoma or well-differentiated angiosarcoma, the follow-up of the patients of this series demonstrated that the vascular proliferations arisen in irradiated skin invariably showed a benign biologic behavior.

Actins↗